From 41c3c496ff507554da1c6099c600809608bdbb81 Mon Sep 17 00:00:00 2001 From: Jamie Gennis Date: Tue, 29 Oct 2013 13:36:12 -0700 Subject: [PATCH] DispSync: remove delay when enabling vsync events This change fixes a bug that caused an extra frame of latency when enabling vsync event callbacks in DispSync. The bug was related to the logic that prevents the two events from firing with very little time between them due to updates to the vsync model. Bug: 11479720 Change-Id: Ie7eaff9e92ffb7b7b6cb4d3d4402c96cbd29af7e --- services/surfaceflinger/DispSync.cpp | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/services/surfaceflinger/DispSync.cpp b/services/surfaceflinger/DispSync.cpp index 167c6f04b..ce07ab56c 100644 --- a/services/surfaceflinger/DispSync.cpp +++ b/services/surfaceflinger/DispSync.cpp @@ -164,7 +164,14 @@ public: EventListener listener; listener.mPhase = phase; listener.mCallback = callback; - listener.mLastEventTime = systemTime(SYSTEM_TIME_MONOTONIC); + + // We want to allow the firstmost future event to fire without + // allowing any past events to fire. Because + // computeListenerNextEventTimeLocked filters out events within a half + // a period of the last event time, we need to initialize the last + // event time to a half a period in the past. + listener.mLastEventTime = systemTime(SYSTEM_TIME_MONOTONIC) - mPeriod / 2; + mEventListeners.push(listener); mCond.signal();